1. Field of the Invention
The invention relates to a motion estimation method, and more particularly to a motion estimation method which utilizes blocks of two frames to determine a motion vector of a block.
2. Description of the Prior Art
During processing video data, a coding method is usually utilized for compressing video data amount. Standards of video processing often comprise several coding methods for satisfying all kinds of coding demands. For example, MPEG-2 (moving picture coding experts group-2) standard is a coding method for suppressing the redundant video information in time domain or in space domain.
In order to suppress the above-mentioned redundant information, a video compressing technique such as a motion compensation technique is usually used. The steps carried out before using the motion compensation technique comprise: dividing a frame into many blocks (known as ‘macroblocks’), which respectively comprise a specific number of pixels; selecting a block among the macroblocks as a target block; searching a reference block similar to the target block from a reference frame; and determining a motion vector according to the positions of the target block and the reference block.
Many methods have been proposed for determining motion vectors, these methods including: L. Liu, E. Feig, “A block-based gradient descent search algorithm for block motion estimation in video coding,” (IEEE Trans. on Circuits and Systems for Video Technology, vol. 6, no. 4, pp. 419-422); P. I. Hosur, K. K. Ma, “Motion vector field adaptive fast motion estimation,” (Second International Conference on Information Communication and Signal Processing, Singapore, 7-10 Dec. 99); and Y. Nie, K. K. Ma, “Adaptive rood pattern search for fast block-matching motion estimation,” (IEEE Trans. on Image Processing, vol. 11, no. 12, pp. 1442-1449, December 2). However, these and other know methods in this art still suffer problems of memory consumption and low efficiency. Consequently, improved methods and systems are still desired.